completed the basic ui and anilist module

app/Utility/observer.py

@@ -0,0 +1,17 @@
+
+# Of course, "very flexible Python" allows you to do without an abstract
+# superclass at all or use the clever exception `NotImplementedError`. In my
+# opinion, this can negatively affect the architecture of the application.
+# I would like to point out that using Kivy, one could use the on-signaling
+# model. In this case, when the state changes, the model will send a signal
+# that can be received by all attached observers. This approach seems less
+# universal - you may want to use a different library in the future.
+
+
+class Observer:
+    """Abstract superclass for all observers."""
+
+    def model_is_changed(self):
+        """
+        The method that will be called on the observer when the model changes.
+        """